Bicycle rear derailleur

ABSTRACT

A bicycle rear derailleur includes a base portion, a coupling mechanism, a moveable member, a pivot shaft, a tension plate, a biasing spring and a guide plate. The base portion attaches to a bicycle frame. The coupling mechanism has first and second ends. The first end is coupled to the base portion and the second end is movable relative to the base portion. The movable member is coupled to the second end and the pivot shaft is coupled to the movable member. The tension plate is pivotally coupled to the movable member by the pivot shaft and supports a chain tensioning pulley. The biasing spring is operatively coupled to the movable member and the tension plate for biasing the tension plate in a chain tensioning direction. The guide plate is pivotally coupled to the pivot shaft in a non-biased manner and supports a chain guiding pulley.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a bicycle rear derailleur. Morespecifically, the present invention relates to a bicycle rear derailleurhaving a tension plate that supports a chain tensioning pulley and aguide plate that supports a chain guiding pulley where the guide plateand tension plate are mounted to a pivot shaft with independent pivotalmovement with respect to one another.

2. Background Information

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One component that has been extensively redesigned is thebicycle rear derailleur.

Rear derailleurs are well known and typically include a linkagestructure that includes a moveable member. The moveable member isselectively manipulated in a conventional manner to position a guidingpulley to guide a chain between a plurality of gears in a gear sprocketset.

An optimal shifting condition preferably includes positioning theguiding pulley at equal distances from each of the gears in the gearsprocket set for each gear setting position of the derailleur.Specifically, with the chain around a first gear, the guiding pulley isa first distance away from the first gear. With the chain around asecond gear, the guiding pulley is a second distance away from the firstgear. With the chain around a third gear, the guiding pulley is a thirddistance away from the first gear. In optimal shifting conditions, thefirst, second and third distances are equal or close to being equal.

Unfortunately, the geometry of gear derailleurs and gear sprocket setsis such that the first, second and third distances are not equal and maydiffer undesirably. Therefore, optimal shifting conditions are not beingachieved.

In view of the above, it will be apparent to those skilled in the artfrom this disclosure that there exists a need for an improved rearderailleur that can achieve more optimal shifting conditions. Thisinvention addresses this need in the art as well as other needs, whichwill become apparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a rear derailleur witha tension plate and a guide plate that pivot independently from oneanother on the same pivot shaft.

Another object of the present invention is to provide a rear derailleurwith a guide pulley that operates with minimal variations in distancesfrom respective gears in a gear sprocket set.

The foregoing objects can basically be attained by providing a bicyclerear derailleur with a base portion, a coupling mechanism, a movablemember, a pivot shaft, a tension plate and a guide plate. The baseportion is arranged and configured for attachment to a bicycle frame.The coupling mechanism has a first end and a second end. The first endis coupled to the base portion and the second end is movable relative tothe base portion. The movable member is coupled to the second end of thecoupling mechanism. The pivot shaft is coupled to the movable member.The tension plate is pivotally coupled to the movable member by thepivot shaft and the tension plate supports a chain tensioning pulley.The guide plate is coupled to the pivot shaft and is disposed adjacentto the tension plate with the tension plate disposed between the movablemember and the guide plate. Further, the guide plate supports a chainguiding pulley.

As a result, the chain guiding pulley is free to pivot relative to thepivot shaft. In other words, the axis of rotation of the chain guidingpulley is spaced apart from and independent of the axis of rotation ofthe tension plate.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a side elevational view showing a bicycle that includes a rearderailleur in accordance with the present invention;

FIG. 2 is a fragmentary rear elevational view showing a portion of therear wheel of the bicycle, including a gear set and the rear derailleurin accordance with the present invention;

FIG. 3 is a front perspective view of a rear portion of the bicycleshowing the rear derailleur in accordance with the present invention;

FIG. 4 is a rear perspective view of the rear portion of the bicycle andthe rear derailleur in accordance with the present invention;

FIG. 5 is an exploded view of a portion of the rear derailleur showing asupport bracket, a base member and a B-shaft in accordance with thepresent invention;

FIG. 6 is a side view of an outward side of the rear derailleur shownremoved from the bicycle in accordance with the present invention;

FIG. 7 is a side view of an inward side of the rear derailleur shownremoved from the bicycle in accordance with the present invention;

FIG. 8 is another exploded view showing a tension plate, a guide plate,a tensioning pulley and a guide pulley shown removed from the rearderailleur in accordance with the present invention;

FIG. 9 is another rear perspective view showing a portion of a frame ofthe bicycle, the support bracket, the base member, the B-shaft and aportion of the derailleur linkage assembly with other portions of thederailleur removed to provide greater clarity, in accordance with thepresent invention;

FIG. 10 is a cross-sectional view of a portion of the rear derailleurtaken along the line 10-10 in FIG. 9, showing details of the B-shaft,support bracket and the base member in accordance with the presentinvention;

FIG. 11 is a cross-sectional view of another portion of the rearderailleur taken along the line 11-11 in FIG. 3, showing details of apivot shaft that supports the tension plate and the guide plate, and apulley shaft that supports the guide pulley in accordance with thepresent invention;

FIG. 12 is a schematic side view of the rear portion of the bicycleshowing the guide pulley and the tensioning pulley of the rearderailleur, along with a gear set and a chain of the bicycle inaccordance with the present invention;

FIG. 13, 14 and 15 are schematic drawings showing pivoting movement ofthe pulley shaft relative to the pivot shaft in several gear settingpositions in accordance with the present invention;

FIG. 16 is a side view of the rear derailleur shown in a first gearsetting position in accordance with the present invention;

FIG. 17 is a side view of the rear derailleur shown in an offsetposition enabled for gear shifting into another gear setting position inaccordance with the present invention; and

FIG. 18 is a schematic rear view of the gear set and guide pulley of therear derailleur showing the approximate distance between each gearsprocket of the gear sprocket set and the guide pulley in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Selected embodiments of the present invention will now be explained withreference to the drawings. It will be apparent to those skilled in theart from this disclosure that the following descriptions of theembodiments of the present invention are provided for illustration onlyand not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

Referring initially to FIG. 1, a bicycle 10 is illustrated in accordancewith a first embodiment of the present invention. The bicycle 10includes a frame 12 that has a front end 14 and a rear end 16. A rearderailleur 18 in accordance with the present invention is mounted to therear end 16 of the frame 12, as described in greater detail below.

The front end 14 of the frame 12 is coupled to and supports a handlebar20. A gear shifting mechanism 22 is mounted to the handlebar 20. Thegear shifting mechanism 22 operates in a conventional manner to controlmovement of the rear derailleur 18 to position a chain C between gearsetting positions P₁ thru P₉ (see FIG. 18). The gear shifting mechanism22 maintains movement control of the rear derailleur 18 via a controlcable assembly 24 that extends between the gear shifting mechanism 22and the rear derailleur 18. The control cable assembly 24 preferablyincludes an outer sheath 24 a and an inner cable 24 b, as described ingreater detail below.

As shown in FIGS. 4 and 5, the rear end 16 of the frame 12 is formedwith a rear wheel support portion 26. As shown in FIG. 5, the rear wheelsupport portion 26 includes a rear wheel slot 28, a threaded aperture 30and an adjuster receiving protrusion 32. The adjuster receivingprotrusion 32 is formed with an adjuster engaging surface 34. Thethreaded aperture 30 is spaced apart from and is positioned generallyvertically below and rearward from the rear wheel slot 28, relative tothe bicycle frame 12. The threaded aperture 30 serves as a derailleursupport aperture for supporting a B-shaft of the derailleur 18, as isdescribed in greater detail below.

The rear wheel support portion 26 supports a rear wheel 36. The rearwheel 36 includes a rear wheel axle 38 which forms a part of a quickrelease axle assembly 40. The rear wheel axle 38 further supports aconventional gear sprocket set 42, as shown in FIG. 2. The quick releaseaxle assembly 40 includes the rear wheel axle 38, a nut 43 and a quickrelease lever 44 providing for easy removal and installation of the rearwheel 36.

The rear derailleur 18 is mounted to the rear wheel support portion 26adjacent to the gear sprocket set 42 allowing rapid installation andremoval of the rear wheel 38, in a manner described in greater detailbelow.

Referring now to FIGS. 2-5 and 8, the rear derailleur 18 basicallyincludes a support bracket 50, a base member 52, a support shaft 54shown in FIG. 5 (also referred to as the B-shaft), a derailleur linkageassembly 56, a moveable member 116, a pivot shaft 58 shown in FIG. 8(also referred to as a P-shaft), a tension plate 60 and a guide plate62. The support bracket 50, the base member 52 and the support shaft 54basically constitute a base portion that supports the rear derailleur 18on the rear wheel support portion 26 of the rear end 16 of the frame 12.

Referring again to FIG. 5, the support bracket 50 is a stationary memberwith the rear derailleur 18 installed on the bicycle 10. The supportbracket 50 basically includes a first end 66, a second end 68, a bentportion 70 and a cable guide portion 72. The first end 66 is a firstmounting portion that is configured for releasable attachment to therear wheel axle 38. Specifically, the first end 66 is formed with ahook-like configuration or shape that defines a recess 76. When supportbracket 50 is installed on the rear wheel support portion 26 of the rearend 16 of the frame 12, the recess 76 is preferably aligned with therear wheel slot 28 in the rear wheel support portion 26, as shown inFIG. 5. Therefore, when the rear wheel axle 38 is installed in the rearwheel slot 28, the rear wheel axle 38 also extends into the recess 76.When the quick release axle assembly 40 is tightened in a conventionalmanner, the first end 66 is pressed and retained in position against therear wheel support portion 26 of the frame 12. Further, when the quickrelease axle assembly 40 is released, the rear wheel axle 38 is easilyremoved from the rear wheel support portion 26 without removing the rearderailleur 18. Hence, the first end 66 engages and is held in positionby the rear wheel axle 38.

The rear wheel axle 38 is installed in the rear wheel slots 28 of therear wheel support portion 26, as indicated in FIGS. 4 and 5. Since thequick release axle assembly 40 is included with the rear wheel 36, therear wheel 36 can be quickly removed and installed on the frame 12 bymanipulation of the quick release lever 44.

The first end 66 also has a generally flat plate-like shape such thatthe first end 66 makes solid planar contact with the rear wheel supportportion 26 and the nut 43, as indicated in FIG. 2. The second end 68 ofthe support bracket 50 is a second mounting portion. The second end 68 agenerally flat plate-like shape and includes an aperture 80, a firstrecess 81 a (FIGS. 5 and 10) and a second recess 81 b (FIG. 10) formedtherein. The aperture 80 is co-axially aligned with the first and secondrecesses 81 a and 81 b. The bent portion 70 is formed between the firstend 66 and the second end 68. The bent portion 70 extends between thefirst end 66 and second end 68 providing a planar or lateral offset tothe first end 66 and the second end 68. Specifically, the first end 66and the second end 68 are generally parallel to one another but arespace apart by a distance corresponding to the length of the bentportion 70. Further, the first end 66 of the support bracket 50 isaxially offset from the second end 68 relative to an axial direction ofthe support shaft 54. As well, the first end 66 of the support bracket50 is horizontally and vertically offset from the second end 68 wheninstalled on the rear end 16 of the frame 12, as shown in FIGS. 2 and 5.

Again with reference to FIG. 5, the cable guide portion 72 is formed onan upper region of the first end 66 of the support bracket 50. The cableguide portion 72 is a cable receiving portion that includes a hollowinterior through which the inner cable 24 b of control cable assembly 24extends. The outer sheath 24 a of the control cable assembly 24 has adiameter larger than the hollow interior of the cable guide portion 72.Consequently, the outer sheath 24 a remains in a generally fixedposition with respect to the cable guide portion 72 as the inner cable24 b is moved by the gear shifting mechanism 22. Alternatively, theouter sheath 24a can be inserted into the cable guide portion 72 andabut an inner annular projection (not shown) that restricts movement ofthe outer sheath 24 a but allows the inner cable 24 b to extendtherethrough. Conventional movement of the inner cable 24 b allows gearpositioning control of the movement of the rear derailleur 18.

As shown in FIG. 4 and 5, the base member 52 basically includes asupport end 82 (a support portion), a bent portion 84, a linkageassembly connection portion 86, a cable idler pulley end 88 and anadjuster extension 90 that are all integrally formed as a single member.

The support end 82 of the base member 52 has a generally flat plate-likeshape and contour but is formed with an annular protrusion 92 thatextends perpendicularly away from the support end 82. The annularprotrusion 92 can be integrally formed with the support end 82 of thebase member 52. Alternatively the annular protrusion 92 can be formed asa separate member that engages the support end 82 of the base member 52.An aperture 94 (or apertures) extends through the annular protrusion 92and the support end 82 of the base member 52.

The support end 82 also includes a bushing 98 that is fitted within theaperture 94 in the support end 82 of the base member 52. The bushing 98is longer than the aperture 94 and the annular protrusion 92 and extendsat least partially into the second recess 81 b formed in the second end68 of the support bracket 50, as shown in FIG. 10. With the rearderailleur 18 installed on the frame 12 of the bicycle 10, the aperture94 is aligned with the threaded aperture 30 in the rear wheel supportportion 26 of the rear end 16 of the frame 12. Further, the aperture 80in the second end 68 of the support bracket 50 is also preferablyaligned with the aperture 94 and the threaded aperture 30.

It should be understood from the drawings that the first end 66 of thesupport bracket 50 and the support end 82 of the base member 52 aregenerally co-planar when installed on the rear end 16 of the frame 12.

The bent portion 84 of the base member 52 extends between the linkageassembly connection portion 86 and the support end 82 of the base member52. Specifically, the bent portion 84 provides a planar offset betweenthe linkage assembly connection portion 86 and the support end 82. Asshould be clearly understood from the drawings, the linkage assemblyconnection portion 86 and the support end 82 are offset from one anotherby the bent portion 84.

The linkage assembly connection portion 86 is axially, horizontally andvertically offset from the support end 82 of the base member, relativeto the frame 12 and relative to an axial direction of the support shaft54, as shown in FIGS. 2, 4 and 5. The linkage assembly connectionportion supports a portion of the derailleur linkage assembly 56 in amanner described in greater detail below. The linkage assemblyconnection portion 86 is located between the cable idler pulley end 88and the support end 82 of the base member 52.

The cable idler pulley end 88 of the base member 52 has a shaft 100mounted thereon and a cable idler pulley 102 installed on the shaft 100.As shown in FIG. 4, the inner cable 24 b of the control cable assembly24 extends from the cable guide portion 72 of the support bracket 50around the cable idler pulley 102 and then connects to the derailleurlinkage assembly 56 in a manner described below.

The adjuster extension 90 is preferably formed on or proximate thesupport end 82 of the base member 52. The adjuster extension 90 extendsin a direction away from the second end 68 of the support bracket 50.The adjuster extension 90 is basically a protrusion that is formed witha threaded aperture 104 that extends in a direction generallyperpendicular to the support shaft 54. The threaded aperture 104 isconfigured to receive an adjuster screw 106. When assembled, theadjuster screw 106 contacts the adjuster engaging surface 34 of theadjuster receiving protrusion 32 on the rear wheel support portion 26 ofthe rear end 16 of the frame 12. The adjuster screw 106 provides asimple structure for adjusting an angular stop position of the basemember 52 and the derailleur linage assembly 56 relative to the supportbracket 50 and the frame 12.

The support shaft 54 serves as a B-shaft for the rear derailleur 18 andincludes a shaft portion 108, a head portion 110 and a threaded portion112. The shaft portion 108 is dimensioned to extend through the aperture80 and the bushing 98 in the aperture 94 of the support end 82 of thebase member 52. The head portion 110 at least partially extends into thefirst recess 81a on the support bracket 50 to restrict axial movement ofthe rear derailleur 18 with respect to the support bracket 50, as shownin FIG. 10. The threaded portion 112 is configured to thread into thethreaded aperture 30 in the rear wheel support portion 26. By tighteningthe threaded portion 112 into the threaded aperture 30, the head portion110 presses against the support bracket 50. As a result, the support end82 of the base member 52 is confined between the support bracket 50 andthe rear wheel support portion 26 of the rear end 16 of the frame 12.However, the bushing 98 is dimensioned to prevent the support bracket 50from pressing against the base member 52. Specifically, the base member52 can still rotate or pivot about the bushing 98 even with the supportshaft 54 fully tightened. Hence, the second end 68 of the supportbracket 50, the rear wheel support portion 26 of the rear end 16 and thesupport shaft 54 provide pivotal support for the base member 52.

It should be understood that the tension of the chain C biases the basemember 52 such that the adjuster screw 106 is urged into contact withthe adjuster engaging surface 34 of the rear wheel support portion 26.Therefore, the adjuster screw 106 engaged with the adjuster engagingsurface 34 limits counter clockwise rotational movement of the basemember 52 relative to the rear end 16 of the frame 12.

As shown in FIGS. 3, 4 and 6, the derailleur linkage assembly 56operates in a conventional manner and therefore only a limiteddescription is provided herein for brevity. The derailleur linkageassembly 56 is a coupling mechanism. The derailleur linkage assembly 56basically includes a first pivot link 118 and a second pivot link 120.First ends of the first and second pivot link 118, 120 are movablycoupled to the linkage assembly connection portion 86 of the base member52.

The movable member 116 is moveably coupled to second ends of the firstpivot link 118 and the second pivot link 120 in a conventional manner.Specifically, the first pivot link 118 and the second pivot link 120 canpivot about parallel pivot pins 121 supported on the linkage assemblyconnection portion 86 of the base member 52 and can also pivot aboutparallel pivot pins 123 supported on the moveable member 116. The firstpivot link 118 includes a cable attachment portion 119. The inner cable24 b is attached to cable attachment portion 119 on the first pivot link118 such that as the cable is tightened or loosened, the moveable member116 is selectively moved relative to the base member 52 between aplurality of gear setting positions P₁ thru P₉ , as indicated in FIGS. 2and 18. The pivot pins 121 and 123 extend in a direction that isinclined with respect to the rear wheel axle 38. Consequently, movementof the inner cable 24 b by manipulation of the gear shifting mechanism22 cause the moveable member 116 to move upward and outward ordownwardly and inwardly with respect to the base member 52 and the frame12 of the bicycle 10.

It should be understood from the drawings and the description hereinthat the first and second pivot links 118 and 120 are biased by a spring(not shown) to urge the moveable member 116 to maintain the chain C inthe gear setting position P₁. Consequently, pulling the inner cable 24 bcauses the chain C to move from, for example, gear setting position P₁to a selected one of gear setting positions P₂ thru P₉. When the innercable 24 b is released, the spring (not shown) urges the moveable member116 in a direction bringing the chain C toward or into gear settingposition P₁.

As shown in FIG. 11, the moveable member 116 includes a pivot shaftsupporting portion 122. The pivot shaft supporting portion 122 isgenerally cylindrical in shape and includes an outer side 124, a bicycleframe facing side 126, a partially hollow interior 128 and a retainingaperture 130 that extends into the hollow interior 128. The hollowinterior 128 includes a shaft receiving portion 132 and a springretaining recess 134. The spring retaining recess 134 has an innerdiameter that is larger than an inner diameter of the shaft receivingportion 132, as indicated in FIG. 11. A biasing spring 136 is retainedwithin the spring retaining recess 134. One end of the biasing spring136 is engaged with the tension plate 60 and the other end of thebiasing spring 136 is engaged with the spring retaining recess 134. Theretaining aperture 130 is oriented generally perpendicular to shaftreceiving portion 132.

As shown in FIGS. 8 and 11, the pivot shaft 58 (also known as a P-shaft)is coupled to and supported within the pivot shaft supporting portion122. As shown in FIG. 11, the pivot shaft 58 basically includes aretaining end 140, a bushing supporting portion 142, an annularprotrusion 144 and a guide plate supporting end 146. The pivot shaftsupporting portion 122 of the moveable member 116 is configured withrespect to the pivot pins 121 and 123 such that the orientation of thepivot shaft 58 is generally parallel to the support shaft 54 in each ofthe gear setting positions P₁ thru P₉.

The retaining end 140 is formed with an annular recess 148. A retainingbolt 150 extending through the retaining aperture 130 of the pivot shaftsupporting portion 122 further extends into a portion of the annularrecess 148 of the pivot shaft 58 restricting axial movement of pivotshaft 58.

The bushing supporting portion 142 supports a tension plate bushing 152that is fitted thereon. The tension plate bushing 152 in turn rotatablysupports the tension plate 60 on the retaining bolt 150.

The guide plate supporting end 146 is fitted with a guide platesupporting bushing 154 fixed to the guide plate supporting end of pivotshaft 58. The annular protrusion 144 separates the tension plate bushing152 and the tension plate 60 from the guide plate supporting bushing 154and the guide plate 62. It should be understood from FIG. 11 that thetension plate 60 can be press fitted on to the tension plate bushing 152and the tension plate bushing 152 can freely rotate about the pivotshaft 58. Alternatively, the tension plate 60 can be loose fitted aroundthe tension plate bushing 152 and the tension plate bushing 152 pressfitted onto the pivot shaft 58.

As shown in FIGS. 3, 6, 7 and 8, the tension plate 60 has a first end 60a and a second end 60 b. The first end 60 a is offset from the secondend 60 b. In other words, the tension plate 60 is not flat throughoutits length. Specifically, the first end 60 a is offset from the secondend 60 b by a distance approximately equal to or slightly greater thanthe thickness of the guide plate 62.

As shown in FIGS. 3 and 11, the tension plate 60 is rotatably fixed tothe pivot shaft 58. The tension plate 60 is therefore pivotally attachedto the moveable member 116. Further, the tension plate 60 is disposed onthe bicycle frame facing side 126 of the pivot shaft supporting portion122. The tension plate 60 is spring biased by the biasing spring 136 formovement in a chain tensioning direction D (as shown in FIG. 6) relativeto the pivot shaft supporting portion 122 of the moveable member 116.Specifically, one end of the biasing spring 136 engages the hollowinterior 128 of the pivot shaft supporting portion 122 and the other endof the biasing spring 136 engages the tension pulley 60. The tensionplate 60 rotatably supports a tensioning plate 160 and a chain retainer162, as shown in FIG. 8.

As shown in FIG. 11, the guide plate 62 is supported on the pivot shaft58 independent from the spring 136 biasing the tension plate 60. Theguide plate 62 is rotatably fixed to the pivot shaft 58 by the guideplate supporting bushing 154. The guide plate supporting bushing 154 ispress fitted onto the pivot shaft 58 with the guide plate installed onthe guide plate supporting bushing 154. However, the guide plate 62 isfree to rotate on the guide plate supporting bushing 154 relative to thepivot shaft 58. As indicated in FIG. 11, the guide plate 62 is disposedadjacent to the tension plate 60 but is free to rotate independently ofthe tension plate 60. Further, the tension plate 60 is disposed betweenthe guide plate 62 and the bicycle frame facing side 126 of the pivotshaft supporting portion 122 of the moveable member 116.

As shown in FIGS. 8 and 11, the guide plate 62 supports a pulley shaft166 that is spaced apart from and generally parallel to the pivot shaft58. The pulley shaft 166 is press fitted into an aperture 167 formed inthe guide plate 62. The pulley shaft 166 rotatably supports a chainguiding pulley 168 mounted on the pulley shaft 166. A chain retainingplate 170 is fixed to the pulley shaft 166 by a fastener 172, asindicated in FIG. 8. The chain retaining plate 170 interlocks with arearward portion of the guide plate 62 thereby preventing rotation ofthe chain retaining plate 170 with respect to the guide plate 62. Thechain retaining plate 170 is spaced apart from the guide plate 62 withthe chain guiding pulley 168 disposed there between.

It should be understood from the drawings and the description hereinthat the chain guiding pulley 168 and the tensioning pulley 160 aregenerally co-planar. The offset between the first end 60 a and thesecond end 60 b of the tension plate 60 is dimensioned to ensure thatthe chain guiding pulley 168 and the tensioning pulley 160 areapproximately or generally co-planar.

The chain guiding pulley 168 is configured to selectively guide thechain C onto one of the gear rings in the gear sprocket set 42.Specifically, the gear shifting mechanism 22 is used by a cyclist tomove the inner cable 24 b changing the orientation of the first pivotlink 118 and the second pivot link 120, thereby moving the moveablemember 116. Movement of the moveable member 116 causes the chain guidingpulley 168 to move the chain C between the gear setting positions P₁thru P₉. For example, in the gear setting position P₁, the chain Cengages the rightmost gear ring in the gear sprocket set 42 shown insolid lines in FIG. 2. With the gear shifting mechanism 22 manipulatedaccordingly, the chain C is moved to engage the leftmost gear ring inthe gear sprocket set 42 or the gear setting position P₉ as shown indashed lines in FIG. 2.

As shown in FIGS. 11-15, the guide plate 62 pivots about the pivot shaft58. As the chain C changes locations and shifts to a different gear ringor gear setting position with respect to the gear sprocket set 42, theguide plate 62 can pivot about the pivot shaft 58. The guide plate 62can pivot in this manner because the pulley shaft 166 is spaced apartfrom the pivot shaft 58. Further, the biasing spring 136 applies thebiasing force to the tension plate 60, causing the tension plate 60 toapply a force against the chain C in the chain tensioning direction D(FIGS. 6 and 12). The chain C remains taut about the tensioning pulley160, the chain guiding pulley 168 and the selected gear of the gearsprocket set 42 because of the biasing force acting on the tension plate60. The chain C also applies the chain biasing force from the tensionplate 60 to the chain guiding pulley 168. The pulley shaft 166 supportsthe chain guiding pulley 168. Since the pulley shaft 166 is spaced apartfrom the pivot shaft 58, the forces acting on the chain guiding pulley168 cause the guiding plate 62 to pivot about the pivot shaft 58 to, forexample, the approximate positions depicted in FIGS. 13, 14 and 15.

Since the guide pulley 168 rotates about the pulley shaft 166 on theguide plate 62, and the guide plate 62 pivots about the pivot shaft 58,the guide pulley 168 has a small freedom of up and down movement withrespect to the gears on the gear sprocket set 42. The configuration andorientation of the pivot pins 121 and 123 providing movement of themoveable member 116 combined with the pivoting movement of the guideplate 62 provides advantageous shifting condition best explained withrespect to FIG. 18.

Specifically, as the moveable member 116 is moved to position the guidepulley 168 in one of the gear setting positions P₁ thru P₉, the pivotshaft 58 moves relative to the gears of the gear sprocket set 42 as aresult of the orientation of the pivot pins 121 and 123. However, as thepivot shaft 58 is moved, the pivot shaft 58 may not be a constantdistance from each gear of the gear sprocket set 42 in each of the gearsetting position P₁ thru P₉. In other words, in the gear settingposition P₁ the pivot shaft 58 can be a first distance away from thefirst gear. In the gear setting position P₂ the pivot shaft 58 can be asecond distance away from the second gear. In the gear setting positionP₃ the pivot shaft 58 can be a third distance away from the third gear,and so on, in each of the gear setting positions. However, the firstdistance, the second distance and third distance (and so on) may not allbe equal distances.

For optimal shifting performance it is desirable to maintain the guidepulley 168 at distances away from the specific gear corresponding toeach of the gear setting positions P₁ thru P₉ where variations in thedistances are minimized. Minimizing variations in the distances betweeneach gear and the guide pulley 168 is good for derailleur shiftingperformance. In the present invention, the guide pulley 168 is notrotatably mounted on the pivot shaft 58, but is rotatably mounted on thepulley shaft 166 on the guide plate 62. The pivoting movement of thepulley shaft 166 allows the guide pulley 168 to move relative to thegears in the gear sprocket set 42. In other words, the axis of rotation(the pulley shaft 166) is moveable relative to the axis of rotation (thepivot shaft 58) of the tension plate 60 and the guide plate 62. Further,pivoting movement of the guide pulley 168 is directed by the chain C.Specifically, the relative tension and angle of incidence of the chain Crelative to the guide pulley 168 determines the pivoted position of theguide pulley 168. Since the guide plate 62 is not biased by a spring, itcan pivot without much resistance. As a result, the guide pulley 168 canbe positioned in the gear setting position P₁ thru P₉ at distances L₁thru L₉ away from the corresponding gear of the gear sprocket set 42, asindicated in FIG. 18. Using the configuration of the present inventionvariations in the distances L₁ thru L₉ are minimized. The specificshifting conditions afforded by the configuration of the presentinvention provide more desirable shifting conditions.

Another advantage of the present invention lies in the configuration ofthe support shaft 54 (also known as the B-shaft). As described above,the base member 52 is free to pivot about the support shaft 54. As aresult, if the inner cable 24 b is manipulated to shift gear positionsby pulling the inner cable 24 b, the base member 52 can pivot upwardabout the support shaft 54. For example, FIG. 16 shows the base member52 and the derailleur linkage assembly 56 in the gear setting positionP₁. As the inner cable 24 b is pulled, the base member 52 and thederailleur linkage assembly 56 can pivot upward as shown in FIG. 17.

The advantages of the configuration of the support shaft 54 and basemember 52 are best understood when a cyclist is at a stop with the chainC and the guide pulley 168 in the gear setting position P₁. In the gearsetting position P₁ the cyclist requires a significant amount of effortin bringing the bicycle 10 back up to speed from a dead stop. Thecyclist benefits from having the chain C and the guide pulley 168 in thegear setting position P₉ when resuming riding from a dead stop. However,with the bicycle 10 stopped, it is impossible to shift gears because astatic chain cannot move from gear to gear in the gear sprocket set 42.The bicycle 10 and the chain C must be in motion in order to shiftgears.

However, using the present invention, it is possible for a cyclist topre-shift. Specifically, the gear shifting mechanism 22 can manipulatethe inner cable 24b making it shorter, thereby pulling on the basemember 52 moving the base member 52 from the position depicted in FIG.16 to a position similar to that depicted in FIG. 17. This pre-shiftingexerts a force on the derailleur linkage assembly 56 urging the moveablemember 116 into readiness for shifting from the gear setting position P₁to one of the other gear setting positions. Once the bicycle 10 is inmotion, and the chain C begins to move, the chain C is immediately urgedby the guide pulley 168 to the selected different gear setting position.The shifting is accomplished easily because the biasing spring 136biases the tension plate 60 to keep the chain C taut, thereby furtherbiasing the base member 52 back into the position depicted in FIG. 16.In this manner, a pre-shifting is possible using the present invention.More specifically, since the inner cable 24 b wraps around the cableidler pulley 102, when the inner cable 24 b is pulled, the cable idlerpulley 102 acts as a lever point to rotate the base member about thesupport shaft 54. Further, the support bracket 50 further includes thecable guide portion 72 for guiding the inner cable 24 b to ensureadequate leverage for moving the base member 52 during pre-shifting. Aswell, the support bracket 50 provides additional support for the supportshaft 54 to withstand the forces generated by pivoting motion of thebase member 52 when pre-shifting.

Another advantage of the present invention is provided by the shape andconfiguration of the support bracket 50. Since the support bracket 50includes the recess 76, the rear wheel axle 38 can be rapidly removedand re-installed on the frame 12 of the bicycle 10.

As used herein to describe the present invention, the followingdirectional terms “forward, rearward, above, downward, vertical,horizontal, below and transverse” as well as any other similardirectional terms refer to those directions of a bicycle equipped withthe present invention. Accordingly, these terms, as utilized to describethe present invention should be interpreted relative to a bicycleequipped with the present invention.

It should be understood from the drawings and description herein thatthe rear derailleur 18 of the present invention may be used with a gearsprocket set having any of a variety of numbers of gear sprockets and isnot limited to use with a gear sprocket set having nine gear sprockets.

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “member” or “element” when used in thesingular can have the dual meaning of a single part or a plurality ofparts. Finally, terms of degree such as “substantially”, “about” and“approximately” as used herein mean a reasonable amount of deviation ofthe modified term such that the end result is not significantly changed.These terms of degree should be construed as including a deviation of atleast ±5% of the modified term if this deviation would not negate themeaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A bicycle rear derailleur comprising: a base portion arranged andconfigured for attachment to a bicycle frame; a coupling mechanismhaving a first end and a second end, the first end being coupled to thebase portion, the second end being movable relative to the base portion;a movable member coupled to the second end of the coupling mechanism; apivot shaft coupled to the movable member; a tension plate pivotallycoupled to the movable member by the pivot shaft, the tension platesupporting a chain tensioning pulley, the tension plate including amounting end and a pulley supporting end, the mounting end coupled tothe pivot shaft and the pulley supporting end supporting the chaintensioning pulley, the pulley supporting end being laterally offset fromthe mounting end; a biasing spring operatively coupled to the movablemember and the tension plate for biasing the tension plate in a chaintensioning direction without biasing the guide plate; and a guide platebeing rotatably coupled to the pivot shaft to move relative to thetension plate and disposed adjacent to the tension plate with thetension plate disposed between the movable member and the guide platealong the pivot shaft, the guide plate rotatably supporting a chainguiding pulley.
 2. The bicycle rear derailleur according to claim 1wherein the pivot shaft has a flange, and the tension plate is disposedlaterally outwardly from the flange and the guide plate is disposedlaterally inwardly from the flange.
 3. The bicycle rear derailleuraccording to claim 1 wherein the biasing spring is disposed laterallyoutwardly from the tension plate.
 4. The bicycle rear derailleuraccording to claim 1 wherein the guide plate is rotatably coupled to thepivot shaft in a non-biased manner.
 5. The bicycle rear derailleuraccording to claim 1, further comprising: a guide plate bushingrotatably supports the guide plate on the pivot shaft.
 6. The bicyclerear derailleur according to claim 5 wherein the guide plate bushing ispermanently secured to the pivot shaft.
 7. The bicycle rear derailleuraccording to claim 5, further comprising, a tension plate bushingrotatably supporting the tension plate on the pivot shaft.
 8. A bicyclerear derailleur comprising: a base portion arranged and configured forattachment to a bicycle frame; a coupling mechanism having a first endand a second end, the first end being coupled to the base portion, thesecond end being movable relative to the base portion; a movable membercoupled to the second end of the coupling mechanism; a pivot shaftcoupled to the movable member; a tension plate pivotally coupled to themovable member by the pivot shaft, the tension plate supporting a chaintensioning pulley; a biasing spring operatively coupled to the movablemember and the tension plate for biasing the tension plate in a chaintensioning direction without biasing the guide plate; and a guide platebeing rotatably coupled to the pivot shaft in a non-biased manner tomove relative to the tension plate, the guide plate rotatably supportinga chain guiding pulley about a rotational axis that is generallyparallel to and spaced apart from the pivot shaft.
 9. The bicycle rearderailleur according to claim 8, further comprising: a guide platebushing rotatably supporting the guide plate on the pivot shaft.
 10. Thebicycle rear derailleur according to claim 9 wherein the guide platebushing is permanently secured to the pivot shaft.
 11. The bicycle rearderailleur according to claim 10, further comprising, a tension platebushing rotatably supporting the tension plate on the pivot shaft.